Method and apparatus for detecting and treating heart failure

ABSTRACT

Devices and systems provide methods of detecting a heart failure condition of a patient that may be based on one or more respiratory parameters of a patient. In an example embodiment, a monitoring device determines one or more heart failure condition indicators based on a measure of the patient respiratory airflow and/or a measure of treatment pressure. Respiratory parameters such as respiration rate, hypopneas, apneas, Cheyne-Stokes breathing patterns or apnea-hypopnea counts may be compared to thresholds that are selected to represent a change in the condition of a heart failure patient such as an onset of a decompensation event. Results of the comparisons may trigger a pressure treatment change and/or one or more warnings or messages to notify a patient or physician of a pending change to the patient&#39;s heart failure condition so that the patient may more immediately seek medical attention to treat the heart failure condition.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/483,357, filed Jun. 12, 2009, which claims the benefit ofU.S. Provisional Patent Application No. 61/083,596, filed Jul. 25, 2008,the disclosure of which is hereby incorporated herein by reference.

FIELD OF THE TECHNOLOGY

The present technology relates to methods and apparatus for detectingand treating the condition of heart failure.

BACKGROUND OF THE TECHNOLOGY

Heart Failure or Congestive Heart Failure affects approximately fivemillion Americans. CHF is characterized by the Medline Encyclopedia as alife-threatening condition in which the heart can no longer pump enoughblood to meet the demands of the body. Heart failure is almost always achronic, long-term condition, although it can sometimes developsuddenly. This condition may affect the right side, the left side, orboth sides of the heart. As the heart's pumping action is lost, bloodmay back up into other areas of the body, including:

-   -   the liver;    -   the gastrointestinal tract and the extremities (right-sided        heart failure); and    -   the lungs (left-sided heart failure).

With heart failure, many organs do not receive enough oxygen andnutrients. This damages the organs and reduces their ability to functionproperly. Most areas of the body may be affected when both sides of theheart fail.

A common cause of heart failure is hypertension (i.e., high bloodpressure). Another common cause of heart failure is coronary arterydisease (e.g., a heart attack). Other structural or functional causes ofheart failure include:

Valvular heart disease;

Congenital heart disease;

Dilated cardiomyopathy;

Lung disease; and

Heart tumor.

Heart failure is more common with advancing age. Risk factors fordeveloping heart failure include being overweight, having diabetes,smoking cigarettes, abusing alcohol, or using cocaine.

There are devices that may be useful in diagnosing a patient's heartfailure condition. For example, imaging tools may be used. In thisregard, echocardiography is commonly used to support a clinicaldiagnosis of heart failure. This analysis uses ultrasound to determine astroke volume (“SV”). A stroke volume is an amount of blood in the heartthat exits the ventricles with each beat. The analysis may alsodetermine an end-diastolic volume (“EV”) or total amount of blood at theend of diastole. The analysis may also be used to determine the SV inproportion to the EV. This proportion is a value known as the ejectionfraction (“EF”). In pediatrics, the shortening fraction is the preferredmeasure of systolic function. Normally, the EF should be between 50% and70%. However, in systolic heart failure, the EV typically drops below40%. Echocardiography may also be used to identify valvular heartdisease and assess the state of the pericardium (i.e., the connectivetissue sac surrounding the heart). Echocardiography may also aid indeciding what treatments will help the patient, such as medication,insertion of an implantable cardioverter-defibrillator or cardiacresynchronization therapy.

Chest X-rays are another frequently used tool for diagnosing CHF. In thecompensated patient, this may show cardiomegaly (a visible enlargementof the heart), quantified as the cardiothoracic ratio (a proportion ofthe heart size to the chest). In left ventricular failure, there may beevidence of vascular redistribution (“upper lobe blood diversion” or“cephalization”), Kerley lines, cuffing of the areas around the bronchi,and interstitial edema.

An electrocardiogram (ECG/EKG) may be used to identify arrhythmias,ischemic heart disease, right and left ventricular hypertrophy, andpresence of conduction delay or abnormalities (e.g. left bundle branchblock). These results may be evaluated in making a diagnosis of heartfailure.

Blood tests may also be used to diagnose the condition. For example,measures of electrolytes (sodium, potassium), measures of renalfunction, liver function tests, thyroid function tests, a complete bloodcount, and often C-reactive protein if an infection is possible, may beused to diagnose the patient's condition. One specific test for heartfailure determines the level of B-type natriuretic peptide (BNP). Anelevated level of BNP may suggest the existence of heart failure. TheBNP level may differentiate heart failure as a cause of dyspnea fromother conditions that may cause dyspnea. If myocardial infarction is apossibility, cardiac markers may be used in the diagnosis of heartfailure.

A patient's heart failure condition may be the result of coronary arterydisease. The condition may depend on the ability of the coronaryarteries to provide blood to the myocardium. Thus, a coronarycatheterization may also help to identify possibilities forrevascularization through percutaneous coronary intervention or bypasssurgery.

Different measures may be determined to assess the progress of apatient's heart failure condition. A fluid balance or calculation offluid intake and excretion can assist in monitoring a patient'scondition. Similarly, changes in body weight, which may reflect fluidshifts, can be considered.

There is no present gold standard in the diagnosis of heart failure. TheFramingham criteria, which was derived from the Framingham Heart Study,the Boston criteria, the Duke criteria and the Killip classification aresystems that are commonly considered in evaluating a patient for heartfailure.

A functional classification of heart failure may also be considered byclasses defined by the New York Heart Association FunctionalClassification (NYHAFC). A score according to this classification systemgrades the severity of symptoms, and can be used to assess the patient'sresponses to treatment. While it is commonly used, the NYHAFC score maynot be reliably reproducible.

The classes (I-IV) of the NYHAFC system are:

Class I: no limitation is experienced in any activities; there are nosymptoms from ordinary activities.

Class II: slight, mild limitation of activity; the patient iscomfortable at rest or with mild exertion.

Class III: marked limitation of any activity; the patient is comfortableonly at rest.

Class IV: any physical activity brings on discomfort and symptoms occurat rest.

In its 2001 guidelines, the American College of Cardiology/AmericanHeart Association working group introduced four stages of heart failure:

Stage A: a high risk HF in the future but no structural heart disorder;

Stage B: a structural heart disorder but no symptoms at any stage;

Stage C: previous or current symptoms of heart failure in the context ofan underlying structural heart problem, but managed with medicaltreatment;

Stage D: advanced disease requiring hospital-based support, a hearttransplant or palliative care.

It will be appreciated that there is a need in the art for improvedtechniques and devices for addressing the conditions of heart failure.

BRIEF SUMMARY OF THE TECHNOLOGY

An aspect of certain example embodiments of the present technologyrelates to a system for detecting the presence of, or a change incondition (e.g., worsening) of Congestive Heart Failure. In one formthis involves an apparatus for determining and monitoring a respiratoryparameter of a patient. For example, the apparatus monitors a change inthe pattern of apneas and/or hypopneas of a patient and/or a change inCheyne-Stokes breathing. The apparatus may determine a change orworsening of a condition of the patient upon an increase in the numberand/or duration of apneas, hypopneas and/or Cheyne-Stokes breathing.

In some embodiments of the technology, a method involves evaluating aheart failure condition of a patient by measuring a respiratory airflowof the patient and then determining a heart failure condition changeindicator based on the respiratory airflow. The indicator representsinformation about a heart failure condition of the patient.

In some embodiments of the technology, a system monitors a patient toevaluate a heart failure condition of a patient. A typical system mayinclude a patient interface and a flow sensor coupled thereto. The flowsensor generates a respiratory airflow signal representative of thepatient's respiratory airflow from the patient interface. A processor ofthe system is configured to control a determination of the heart failurecondition indicator based on data from the respiratory airflow signal.

In still other embodiments of the technology, a device or apparatusmonitors a patient to evaluate a heart failure condition of a patient.The apparatus or device may include a patient respiratory interface witha sensor coupled with the patient interface. The sensor generates asignal representative of the patient's respiratory airflow. A processor,which may be coupled with the flow sensor, controls a determination of aheart failure condition indicator based on the respiratory airflowsignal.

In one or more of the above embodiments, a warning signal, warning lightor warning message may be generated to inform a patient/user of thetechnology and/or a physician treating the patient. The warning signals,warning lights or messages of the embodiments may be generated andtransmitted between devices to permit remote monitoring and notificationof the patient's heart failure condition. The warning signals, warninglight and/or warning messages will typically be triggered by theevaluation of the heart failure condition indicators.

Some embodiments of the present technology involve a method forevaluating a heart failure condition of a patient during respiratorypressure treatment. The method may include determining a measure oftreatment pressure delivered by a respiratory treatment apparatus with asensor. It may further include determining a heart failure conditionchange indicator with a processor based on the measure of pressure. Themethod may still further include determining a measure of respiration ofthe patient with a sensor, wherein the determining of the heart failurecondition change indicator is further based on the respiration measure.The determining of the indicator may optionally include a thresholdcomparison that detects an increase in a proportion of the measure ofpressure and an increase in an apnea or AHI count during a common timeperiod. In some embodiments, the method may also involve controlling ofa change to a pressure treatment therapy of a respiratory treatmentapparatus in response to one or more determined indicators. This changein control may optionally involve initiating control of ventilationsupport to meet a target ventilation.

Similarly, some embodiments may involve an apparatus for evaluating aheart failure condition of a patient during respiratory pressuretreatment. The apparatus may include a sensor to determine a measure oftreatment pressure delivered by a respiratory treatment apparatus. Aprocessor of the apparatus may determine a heart failure conditionchange indicator based on the measure of pressure. The processor mayalso be configured to determine a measure of respiration of the patientwith data from a sensor so that the processor can determine the heartfailure condition change indicator based on the respiration measure.Optionally, the processor may implement a threshold comparison thatdetects an increase in a proportion of the measure of pressure and anincrease in an apnea or AHI count during a common time period. In someembodiments, the apparatus may include a flow generator coupled with theprocessor such that the processor may be configured to control a changeto a pressure treatment therapy of the respiratory treatment apparatusin response to the determined indicator. Such a change may be initiatingcontrol of ventilation support to meet a target ventilation.

Various aspects of the described example embodiments may be combinedwith aspects of certain other example embodiments to realize yet furtherembodiments.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

FIG. 1 illustrates example components of a monitoring device toimplement a heart failure condition indicator;

FIG. 2 is an example methodology for a device that implements a heartfailure condition indicator for detecting a condition of heart failurepatients;

FIG. 3 illustrates a further monitoring device with additionalcomponents for delivering a pressure treatment therapy to the patient;

FIG. 4 is an example diagnosis flowchart for implementing treatment withdevices that incorporate the heart failure condition indicator of thepresent technology;

FIG. 5 is another example methodology for a device that implements aheart failure condition indicator for detecting a condition of heartfailure patients; and

FIG. 6 illustrates and example warning message based on an example heartfailure condition indicator of the present technology.

DETAILED DESCRIPTION

The present technology involves methods and devices for the treatment ofpatients at risk for heart failure or congestive heart failure orchanges in the condition of these diseases. For example, some heartfailure patients suffer congestive heart failure exacerbation.Congestive heart failure exacerbation is also known as decompensatedheart failure (DHF). Typically, acute decompensation results inpulmonary oedema. Treatment of this condition will typically requirehospitalization for the patient. However, if the potential for acutedecompensation is caught early enough, such as at the earliest stages ofthe onset of pulmonary oedema, it may be treated in a manner that doesnot require hospitalization. The heart failure condition indicator ofthe devices of the present technology provides a basis for detectingsuch changes in congestive heart failure and for notifying the patientor medical providers of the potential need for medical intervention withrespect to the heart failure condition of the patient.

One embodiment of a device for implementing one or more of the heartfailure condition indicators of the present technology is illustrated inFIG. 1. In the embodiment, the heart failure detection device 100implements a heart failure condition change indicator (referenced inFIG. 1 as “HFCI”). The heart failure detection device 100 will typicallyinclude a patient respiratory interface 102, a controller 104 and a flowsensor 106. The patient respiratory interface, which will typicallyinclude a cannula 108 and/or sense tube 110, receives and/or sensesairflow from the patient's respiratory system via the patient's mouthand/or the patient's nares. Alternatively, the patient respiratoryinterface may be implemented with a nasal mask, nose & mouth mask,full-face mask or nasal pillows.

The flow sensor 106 may be coupled with the patient respiratoryinterface. The flow sensor generates a signal representative of thepatient's respiratory flow. For example, flow proximate to the nasalcannula 108 or sense tube 110 may be measured using a pneumotachographand differential pressure transducer or similar device such as oneemploying a bundle of tubes or ducts to derive a flow signal f(t).Alternatively, a pressure sensor may be implemented as a flow sensor anda flow signal may be generated based on the changes in pressure.Although the flow sensor 106 is illustrated in a housing of thecontroller 104, it may optionally be located closer to the patient, suchas in the nasal cannula 108 or sense tube 110. Other devices forgenerating a respiratory flow signal may also be implemented.

Optionally, the heart failure detection device 100 may also includeadditional diagnosis sensors 112. For example, the device may include anoximeter. The oximeter may generate a signal representative of a bloodoxygen level of a patient. A suitable example oximeter or monitor devicemay optionally be any of the devices disclosed in International PatentApplication No. International Application No. PCT/AU2005/001543 (Pub.No. WO/2006/037184) or International Patent Application No.PCT/AU1996/000218 (Pub. No. WO/1996/032055), the disclosures of whichare incorporated herein by cross-reference. As disclosed in theseincorporated PCT applications, the monitor may serve as diagnosissensors that can also optionally provide a blood pressure and/or pulserate monitor for measuring a pulse rate and/or blood pressure of thepatient.

In some embodiments, the diagnosis sensors may also include an ECGmonitor such as the LifeScreen Apnea monitor provided by BiancaMed. Sucha device may be configured to detect cardiac-related characteristics(e.g., ECG signals) and determine respiratory parameters (such ascentral or obstruction apneas, hypopneas, etc.) and other parameters(e.g., arrhythmias) that may be experienced by the patient by analyzingthe ECG signals from the patient. Optionally, these parameters may bedetermined by the analysis algorithms of controller 104 based ontransmission of the ECG data to the controller or they may be determinedby the monitor and be transmitted to the controller 104.

In still further embodiments, the diagnosis sensors may also oralternatively include an ultrasonic screening sensor for detectingobstructive or central apneas by non-contact sensing. For example, thesensor may monitor sound such as by the use of ultrasonic sensors todetect obstructive or central apneas, hypopneas and other respiratoryparameters from the signals measured by the sensors. Such non-contactbased measures may then be implemented for monitoring of the patient'scondition as discussed in more detail herein. Thus, the data from thesensors may be transmitted to the controller 104 for use and analysis bythe controller. Such a sensor may be implemented in a heart failuredetection device of the present technology without the use of acontact-based sensor or without the use of a mask or cannula that mayotherwise be used with a flow sensor for a more direct measure ofpatient airflow. Thus, in this embodiment no patient intervention isrequired for the diagnosis sensing.

In some embodiments, the diagnosis sensors may include a movementsensor. For example, a suprasternal notch sensor or chest band may beimplemented to generate a movement signal that is indicative of patientrespiration. Other suitable sensors may include the movement sensingdevices disclosed in International Patent Application No.PCT/AU1998/000358 (Pub. No. WO/1998/052467), the disclosure of which isincorporated herein by cross-reference. The movement sensors thus mayprovide a measure of patient respiration and may be used as analternative to a flow sensor or in conjunction with other flow sensorsin the determination of respiratory parameters as discussed herein.

The signals from the sensors may be sent to the controller 104. Optionalanalog-to-digital (A/D) converters/samplers (not shown separately) maybe utilized in the event that supplied signals from the sensors are notin digital form and the controller is a digital controller. Based on thesignals from the sensor(s), the controller assesses the changing heartfailure condition of the patient with one or more heart failurecondition indicators HFCI.

The controller may optionally include a display device 116 such as oneor more warning lights (e.g., one or more light emitting diodes). Thedisplay device may also be implemented as a display screen such as anLCD. Activation of the display device 116 will typically be set by thecontroller based on an assessment of the particular heart failurecondition change indicators implemented by the heart failure detectiondevice 100. The display device may be implemented to visually showinformation to a user of the heart failure detection device 100 or aclinician or physician. The display device 116 may also show a graphicuser interface for operation of the heart failure detection device 100.User, clinician or physician control of the operation of the heartfailure detection device 100 may be based on operation of input switches118 that may be sensed by the controller or processor.

Optionally, the controller may also include a communications device 120for receiving and/or transmitting data or messages by the heart failuredetection device 100. For example, the communications device may be awireless transceiver such as Bluetooth or WIFI transceiver. Thecommunications device may also be a network communications device suchas a phone modem and/or network card and may be implemented to sendmessages via the internet directly or through a computer to which theheart failure detection device may be docked. In general, thecommunications device 120 may be used to transmit warnings or messagesto a clinician or physician assessable apparatus 122 such as amulti-patient monitoring system that allows a physician to review datafrom remote patient data recording devices such as the heart failuredetection device 100. In these systems, a database is provided to recordpatient monitoring data. Physicians or clinicians may receive a report,or warning that the patient may require closer observation, or should bebrought to hospital.

The controller 104 will also typically include a processor 114configured to implement particular control methodology such as thealgorithms described in more detail herein. Thus, the controller mayinclude integrated chips, a memory and/or other control instruction,data or information storage medium. For example, programmed instructionsencompassing such a control methodology may be coded on integrated chipsin the memory of the device. Such instructions may also or alternativelybe loaded as software or firmware using an appropriate data storagemedium. With such a controller or processor, the device can be used fordetermining and analyzing many different parameters associated with thepatient's condition based on data from the sensors. Thus, the processormay control the assessment of a heart failure condition indicator HFCIor heart failure condition change indicator as described in theembodiments discussed in more detail herein.

One example methodology or algorithm of the controller 104 of the heartfailure detection device 100 is illustrated in the flow chart of FIG. 2.Generally, the heart failure detection device 100 may monitorrespiratory-related characteristics such as the patient respiratoryairflow with at least one of the flow sensors or a respiratory-relatedcharacteristic deriving device as previously described. For example, instep 200 the respiratory airflow of the patient may be measured andprovided to a processor of the controller.

Based on the analysis algorithms implemented in the controller 104, theheart failure detection device will then determine one or morerespiratory-based parameters from the measure of respiratory airflow orother sensor data in step 202.

For example, a respiratory parameter may be a respiratory rate, numberof apneas, a number of hypopneas or an Apnea-Hypopnea Index (AHI). Tothis end, based on the continuous airflow signal from the sensors and/orother sensor input, the processor may analyze patterns of patient data,such as patterns of the airflow signal, patterns of an ECG signal, etc.,to detect occurrences of apneas and/or hypopneas. Methods and apparatusfor detecting apneas and hypopneas are described in U.S. Pat. No.5,704,345, the contents of which are hereby incorporated herein bycross-reference. An “apnea” may be considered a cessation of breathingby the patient for more than 10 seconds. A hypopnea may be defined as areduction in ventilation to between about 30% to about 70% of normalventilation. The AHI may be calculated as the number of apneas andhypopneas in a particular time period such as an hour, in a day orduring a particular sleep session. Other forms of an AHI may also beimplemented.

Other respiratory-based parameters may also be determined. For example,the processor may also be configured to determine a number ofCheyne-Stokes breaths during a particular time interval such as an hour,in a day or a particular sleep session. One suitable measure may be thedetection of a number of Cheyne-Stokes epochs. An example methodologyfor a detection of Cheyne-Stokes epochs from a flow signal is describedin International Patent Application No. PCT/AU2005/001942 (Pub. No.WO/2006/066337), the disclosure of which is hereby incorporated hereinby cross-reference. Optionally, or alternatively, other sensors may beutilized to detect events of Cheyne-Stokes Respiration (CSR) forimplementation with the heart failure change indicators of the presenttechnology. For example, oximetry may be utilized to assess a presenceof CSR.

In step 204, the controller 104 will then compare one or more of thedetermined respiratory parameters and/or patient parameters to one ormore thresholds. Typically, each threshold is chosen so that the resultsof the comparison indicate a change in the heart failure condition ofthe patient such as the patient beginning to experience an onset ofacute decompensation. For example, a determined respiratory parametersuch as the AHI may be compared to a prior AHI for the patient or anaverage AHI for the patient from a previous time frame, such as one ormore prior monitoring sessions. A present change to the AHI (such as anincrease or a decrease or a certain amount of increase or decrease) overa previous determined AHI may be taken as a heart failure conditionchange indicator. For example, an increase of ten or more may beconsidered indicative of a change in the heart failure condition of thepatient. More complex thresholds indicative of changes in the AHI mayalso be assessed as the heart failure condition change indicator. Forexample, increases in the AHI for two or more consecutive days ofmonitoring sessions may be taken as the heart failure condition changeindicator HFCI. Furthermore, the thresholds may be selected to considerhow significant the change or increases are in AHI such as ignoringsmall changes or small increases (e.g., 2 or fewer).

Alternately, or in addition, a heart failure change indicator may bebased on the determined Cheyne-Stokes breathing patterns or epochs andone or more thresholds. For example, a count of Cheyne-Stokes epochsfrom a current session may be taken as the respiratory parameter and maybe compared to a prior count of Cheyne-Stokes epochs for the patient oran average number of epochs for the patient from a previous time frame,such as one or more prior monitoring sessions. A present change to theepoch count (such as an increase or a decrease or a certain amount ofincrease or decrease) over a previous determined epoch count may betaken as a heart failure condition indicator. Still more complexthresholds indicative of changes in the epoch may also be assessed asthe heart failure condition indicator. For example, increases in theepochs for two or more consecutive days of monitoring sessions without acomparable decrease over the same consecutive day time frame in thefollowing days may be taken as the heart failure condition indicator.

Optionally, a heart failure indicator may be based on the results of thecomparison of several thresholds and several respiratory parameters orpatient parameters. For example, an increase in the AHI over severalsessions coupled with an increase in the Cheyne-Stokes epoch count overseveral sessions may collectively be taken as a heart failure conditionchange indicator.

In some embodiments, one or more of the heart failure conditionindicators may also be based on a threshold comparison involvingmeasures of heart rate, blood pressure and/or blood-oxygen levels. In anexample of such an embodiment, a measured ratio of O₂ to CO₂ as itchanges over time may be compared to a threshold such as a prior measureof the ratio. A certain level of change in the measure may be considereda heart failure change indicator. Still other patient parameters ormeasures may also be implemented as a heart failure change indicatorwith the present technology. Suitable examples may include heart-ratevariability metrics (e.g., measures of sympathovagal balance), cardiopulmonary coupling (e.g., correlation of pulse and breathing), arterialCO₂ tension (e.g., non-invasive estimate via trans-cutaneous CO₂ orend-tidal CO₂) and/or one or more photoploethysmogram-derived indices(e.g., relative respiratory effort and/or variation thereof, arterialstiffness, cardiopulmonary coupling, HRV, etc.).

Moreover, one or more of these patient parameters or measures may becompared with one or more thresholds. The results of one or more ofthese comparisons may then serve as a heart failure change indicator ormay be combined with one or more other respiratory-based parameters toserve as a heart failure condition change indicator. For example, adecrease in an average pulse rate of a patient over several sessionscombined with an increase in a number of epochs during the same sessionsmay be taken as a heart failure condition indicator.

Thresholds associated with these patient parameters such as therespiratory-based parameters may be determined through empiricalanalysis of the conditions and changes experienced by congestive heartfailure patients.

An apparatus or device in accordance with the invention provides aconvenient way to monitor patients and may even be utilized while theysleep. Thus, in optional step 206 of FIG. 1, when the device determinesthat a change in the patient's condition is a worsening state of thepatients heart based on the heart failure condition indicators HFCI, theheart failure condition change indicators may be used to trigger thedevice to provide a warning or message in a form suitable for thepatient and/or clinicians to be aware of the status of the patient'sheart so that the patient may more efficiently receive the care that isnecessary.

The warning or messaging of the system may take a number of forms. Forexample, the controller, in response to an affirmative heart failurecondition change indicator, may activate a status light (e.g., an LED oran icon on a display screen or LCD) of the monitoring device. A moredetailed message concerning the assessment of the indicator may also bedisplayed on the display screen. Optionally, the controller may also, oralternatively, send a message to a clinician of physician. Such amessage may take the form of a wired or wireless communication. Forexample, the controller may generate a message via a paging system suchas by automatically dialing a paging system. The controller may also beconfigured to generate an automated voice phone call message. Thecontroller may also send the message by a fax transmission. In someembodiments, the controller may also send a message via any internetmessaging protocol, such as an email message, or by any other internetdata file transport protocol. The messages may even be encrypted to keeppatient information confidential. A typical message may identify thepatient. Such a message may also include the data of the changesrecorded by the system any other recorded patient information. Themessage may even express that the patient should be considered foradditional heart failure treatment or an evaluation due to the detectionof a potential decompensation event.

Thus, an example embodiment of a display or warning that may bepresented to a patient or physician by the device may be a warningmessage such as a graphic or textual message. The message may bedisplayed on the device or a remote device based on the evaluation ofone or more of the programmed heart failure condition change indicatorsHFCI. For example, the warning message may be based on an increase inthe measured Cheyne-Stokes epochs count (e.g., an increase of more than20 units or some other number of units from a set of previous dayscounts (e.g., two days)). The warning message may also be based on anincrease in the AHI index (e.g., an increase by more than 10 units orsome other number of units from a set of previous days indices (e.g.,two days)). Such a heart failure condition indicator(s) could triggerthe message(s). Still optionally, the message may also be based on acollective combination of the two example increases such that themessage is triggered only when both conditions are met.

While a simple warning message may be utilized, graded levels of warningmessages may also be generated to describe the patient's heart failurecondition as multiple different heart failure condition indicators or arepeated heart failure condition indicator collectively triggers thedifferent messages based on the severity of the detected conditions. Forexample, one heart failure condition indicator may trigger an initialwarning message on a certain day. However, a different message, such asone with a higher level of urgency, may be generated by a second anddifferent heart failure condition indicator on a subsequent day based onthe previously illustrated collective condition that involves both theAHI and the Cheyne-Stokes epoch respiratory parameters. In such anembodiment, after the first message, the second message may moreurgently warn that the patient should immediately contact a physicianfor a medical examination. In this manner, the device may monitor orstore data concerning each warning so that the warnings may beprogressively altered or generated based on prior warnings and/or heartfailure change indicators.

Furthermore, while all of these messages could be directed by thecontroller 104 to the patient via the display device 116 of the heartfailure detection device 100 and the physician via the communicationsdevice 120, in some embodiments, the messages could be directed moreselectively. For example, the first message may be only transmitted to aphysician or clinician by only transmitting the message to a physiciansystem 122 through the communications device 120 without showing it onthe display device 116. However, the second message, which may be a moreurgent message, could then be actively displayed on the display device116 in addition to transmitting it to the physician system 122. Anaudible alarm from an optional speaker controlled by the controller ofthe device may also be implemented. Use of an audible alarm may dependon the urgency of the message.

While the heart failure condition indicator technology may be includedin a monitoring device such as the heart failure detection device 100,the technology may also be combined with other devices. For example, thetechnology may be implemented in devices used for monitoring otherpatient conditions. Thus, the technology may be implemented in suchdiagnosis or screening devices as the APNEA LINK (ResMed), EMBLETTA(Flaga), RUSleeping™ (Respironics) and the E-series (Compumedics) etc.Optionally, it may be implemented with a non-contact sleep monitoringdevice such as a non-contact AHI screener (e.g., BiancaMed biomotionsensor, which detects movement, respiration, respiratory effort, and/orheart rate via low power pulses of radio frequency energy.)

By way of further example, the heart failure detection device may beimplemented in respiratory treatment devices. Thus, the technology maybe implemented in automatic diagnosis and treatment devices such as theResMed AUTOSET series of devices including the AUTOSET CS, and adaptiveservo ventilation devices, such as the ResMed VPAP Adapt SV. Forexample, FIG. 3 illustrates a respiratory treatment device that mayimplement the technology described herein.

In reference to FIG. 3, the monitoring and treatment device 400 mayserve as the heart failure detection device 100. Thus, the device mayinclude a patient respiratory interface 402, such as a mask 409 anddelivery tube 410, like the device of FIG. 1. In such a device, thedelivery tube 410 may serve as the sense tube 110. The monitoring andtreatment device may also include a flow sensor 406, a controller 404,display device 416, switches 418, communications device 420 anddiagnosis sensors 412 comparable to the components previously describedwith respect to the device of FIG. 1. The device may also communicategenerated messages to the physician system 422 as previously discussed.

However, the monitoring and treatment device 400 of FIG. 3 may alsooptionally be configured to provide a respiratory pressure treatmentfrom a flow generator such as a servo-controlled blower 424. The devicemay further include a pressure sensor 106, such as a pressure transducerto measure the pressure generated by the blower 102 and generate apressure signal p(t) indicative of the measurements of pressure.

Based on flow f(t) and pressure p(t) signals, the controller 404 with aprocessor 414 generates blower control signals. For example, thecontroller may generate a desired pressure set point and servo-controlthe blower to meet the set point by comparing the setpoint with themeasured condition of the pressure sensor. Thus, the controller 404 maymake controlled changes to the pressure delivered to the patientinterface by the blower 102. Optionally, such changes to pressure may beimplemented by controlling an exhaust with a mechanical release valve(not shown) to increase or decrease the exhaust while maintaining arelatively constant blower speed. With such a controller or processor,the apparatus can be used for many different pressure treatmenttherapies, such as the pressure treatments for sleep disorderedbreathing, Cheyne-Stokes Respiration or obstructive sleep apnea (e.g.,CPAP, APAP, Bi-Level CPAP, Auto-VPAP, etc.) by adjusting a suitablepressure delivery equation.

To this end, an example clinical methodology for prescribing and usingsome embodiments of the present technology is illustrated in FIG. 4. Instep 528, a patient is diagnosed with congestive heart failure and maybe at a risk of experiencing acute decompensation. In step 530, thepatient is evaluated for Sleep Disordered Breathing (SDB) or determinedif the patient is being treated for SDB. If the patient does not havethis condition, the patient may be provided a heart failure treatmentdevice 100 in step 538 for use, such as during the patient's sleep.Alternatively, in step 530 if the patient does have Sleep DisorderedBreathing, the patient may be evaluated for Cheyne-Stokes Respiration(CSR) or Obstructive Sleep Apnea (OSA). In the former case, the patientwould be provided a device capable of generating treatment pressures foraddressing CSR in step 536. Alternatively, in the latter case of OSA,the patient would be provided a device capable of generating treatmentpressures for addressing OSA in step 534. In step 540, each of thedevices would monitor and analyze information based on the patient'srespiration to determine the respiratory based parameters as previouslydiscussed with respect to the algorithm of FIG. 2. In step 542, thethresholds of one or more heart failure condition indicators would beevaluated. If a heart failure condition indicator suggests that thepatient is experiencing a worsening or change of the heart failureconduction such as a decompensation event, a warning would be triggeredin step 544. However, if the heart failure condition indicators do notsuggest the presence of such a change in condition, no warning would begenerated and the device would continue to monitor and analyze byreturning to step 540. In this way, the present technology may berealized in different devices depending on the needs of the patientwhile taking advantage of the existing components of other devices thatthe patient may need.

In some embodiments of the present technology as illustrated in FIG. 5,the assessed heart failure condition indicator may also be based on ameasure of pressure associated with a respiratory treatment generated bya treatment apparatus such as, for example, an adaptive servo ventilatoror other respiratory treatment device that detects and responds torespiratory events such as central apneas, hypopneas and/or obstructiveapneas (e.g., an auto-titrating SDB apparatus, auto-end expiratorypressure (EEP) setting apparatus and/or a device that measuresventilation and maintains a target ventilation). Thus, in 600, pressuremay be measured by a sensor of a respiratory treatment apparatus such asan adaptive servo-ventilator. In 602, treatment pressure may then bedetermined based on the pressure measure. Example treatment pressuremeasures may include a peak inspiratory pressure, proportion ofdelivered pressure treatment, median pressure, and/or a level ofpressure support, etc. These measures may be determined by the device ona session by session basis or some other time period. For example, sucha measure may be determined by monitoring a 95th percentile pressuredelivered during a treatment session as described in U.S. Pat. No.7,100,608 assigned to ResMed. Ltd. and filed on Jan. 4, 2002, the entiredisclosure of which is incorporated herein by cross-reference. Suchmeasures may be monitored and compared to one or more suitablethresholds to provide a heart failure condition indication in 604. Thehistory of such measures may be considered over days or months. Forexample, one or more of these measures and suitable threshold(s), suchas a certain amount of change in one or more sessions when compared toone or more prior sessions may serve as the indicator. Thus, theindicator may be based on a recent trend indicating increases in one ormore pressure measures from a prior period of time or prior treatmentsession or sessions and may result in the triggering of a warning in608.

These indicators may also be combined with other indicators previouslydiscussed to yield a sophisticated and synergistic early warning ofdecompensation events. For example, the indicator based on an increaseor a trend of increases in pressure may be combined with an indicatorbased on changes in an apnea and/or hypopnea count during a common setof treatment sessions. For example, a moderate or small increase orincreasing trend in an AHI and/or an apnea count (shown as “AI” in FIG.6) (e.g., obstructive apnea and/or central apnea) by an amount coupledwith an increase or an increasing trend in a treatment pressure measuremay serve as a combined heart failure condition indicator if detectedduring a similar time period. Such a warning that may be generated by adevice based on a several session increase in both 95^(th) percentilepressure and either AHI or AI is illustrated in FIG. 6. As alsoillustrated, the device may optionally generate a report showing orillustrating the analyzed measures that are associated with theparticular heart failure change indicator.

In some embodiments, the positive indication of a detection ofdecompensation from one or more heart failure condition indicators maybe implemented to control an automated change in a treatment therapyprovided by a respiratory treatment apparatus as illustrated at 608 inFIG. 5. For example, upon a positive indication, the treatment controlmethodology of the device may modify control of the flow generator tochange a pressure response of the device. For example, a modification intreatment therapy protocol may be implemented. In one such embodiment,the change in control may cause the respiratory treatment apparatus tobegin to control pressure changes so that a measure of ventilation meetsa target ventilation. For example, a processor of a treatment apparatusmay servo-control the flow generator to deliver a pressure treatmentthat satisfies the target ventilation. A target ventilation may bepredetermined by a physician or automatically set with a learning modeof a respiratory treatment device. Such a device will typically measuredelivered ventilation and adjust the pressure being supplied to thepatient in a manner to ensure that the measured ventilation satisfiesthe target ventilation. Thus, if a patient's respiration causes themeasured ventilation to begin to fall below or rise above the targetventilation over time, the flow generator will compensate with anincrease or decrease respectively in the supplied pressure support. Inthis way, an automatically setting SDB device (e.g., an auto-titratingCPAP or Bi-level device) may begin to function as a servo-controlledventilator in response to the detection of one or several decompensationevents. Optionally, other changes to the pressure control or pressuresettings may be implemented in response to a positive or negativeindication of one or more heart failure condition indicators. Forexample, a negative indication subsequent to a positive indication mayreturn the pressure treatment control protocol from a ventilation targetenforcing protocol to an auto-titrating SDB protocol. By way of furtherexamples, positive indications of decompensation may be implemented tocontrol a modification of the target for ventilation enforcement. Forexample, the target may be increased based on additional detections ofdecompensation. In one such embodiment, a device which enforces acalculated target ventilation (e.g., 90% of a long term ventilationmeasure) may change its target to a predetermined (e.g., clinicianprescribed) and recorded target ventilation such as an estimate of grossalveolar ventilation.

While the heart failure condition indicator technology has beendescribed in several embodiments, it is to be understood that theseembodiments are merely illustrative of the technology. Furthermodifications may be devised within the spirit and scope of thisdescription.

For example, while an integrated device is contemplated by the presenttechnology, the methodology of the components of the devices may beshared across multiple components of a system. For example, a monitoringdevice may simply measure the respiratory data of the patient andtransfer the data to another processing system. The second processingsystem may in turn analyze the respiration data to determine therespiratory parameters used in an analysis of the present technology.The second processing system may also evaluate the heart failurecondition indicators and generate warning messages as described herein,such as by sending one or more of the described messages, in electronicform for example, back to the patient monitoring device for display onthe device to warn the patient.

By way of further example, in some embodiments, the apparatus or systemmay also determine a change that is representative of improvement of aheart failure condition of the patient. For example, a decrease in thenumber and/or duration of apneas, hypopneas, Cheyne-Stokes breathingand/or any other determined change to any respiratory parameters and/orpatient parameters may serve as one or more heart failure conditionindicators as previously discussed. A suitable message may then begenerated based thereon to inform the user and/or physician of thepotential need to revise the patient's medical treatment (e.g., areduction in heart failure related medication, reduction or change inpressure treatment or pressure treatment protocol, etc.) due to thepatient's improvement. In some embodiments, the detected improvement mayeven serve as a control to a change in treatment such as, for example, achange to a pressure treatment setting or a pressure treatment protocolof a respiratory treatment apparatus. For example, an indication ofimprovement may control a change from a protocol that deliversrespiratory support to maintain a ventilation target to one that doesnot, such as a SDB device that treats Cheyne-Stokes Respiration orobstructive sleep apnea (e.g., CPAP, APAP, Bi-Level CPAP or other devicethat detects apnea and/or obstructive events and sets a treatmentpressure to treat the detected event.)

Other variations can be made without departing with the spirit and scopeof the technology.

1-66. (canceled)
 67. A method for evaluating a heart failure conditionof a patient comprising: receiving data representing patient conditionsfrom a non-contact sensor; and determining with a processor a heartfailure condition change indicator based on the non-contact sensor data,the indicator representing information about a change in a heart failurecondition of the patient.
 68. The method of claim 67 wherein thenon-contact sensor data is used to determine a respiratory parameter.69. The method of claim 68 wherein the determining of the heart failurecondition change indicator comprises: comparing the respiratoryparameter with a threshold.
 70. The method of claim 69 wherein thethreshold is representative of a change to the respiratory parameterthat is indicative of onset of acute decompensation.
 71. The method ofclaim 68 wherein the determining of the heart failure condition changeindicator comprises: comparing a change in a pattern of the respiratoryparameter over a number of evaluation sessions.
 72. The method of claim68 wherein the respiratory parameter is an apnea-hypopnea index.
 73. Themethod of claim 68 wherein the respiratory parameter is a Cheyne-Stokesbreathing pattern index.
 74. The method of claim 68 wherein therespiratory parameter is a respiratory rate.
 75. The method of claim 67further comprising generating a warning based on the heart failurecondition change indicator.
 76. The method of claim 75 wherein thewarning comprises an activated light.
 77. The method of claim 75 whereinthe warning comprises a message.
 78. The method of claim 67 furthercomprising transmitting an electronic message including datarepresenting the heart failure condition change indicator.
 79. Themethod of claim 67 further comprising generating a flow of breathablegas at a pressure above atmospheric to the patient during the receivingof the non-contact sensor data.
 80. The method of claim 79, wherein thedetermining the heart failure condition change indicator is furtherbased on a measure of pressure associated with the flow of breathablegas.
 81. The method of claim 80, wherein the measure of pressure is oneof: a peak inspiratory pressure; an end expiratory pressure; a medianpressure; a 95th percentile pressure; and a level of pressure support.82. The method of claim 67 wherein the determining of the heart failurecondition change indicator comprises: determining a plurality ofrespiratory parameters from the non-contact sensor data; and comparingthe respiratory parameters with respective thresholds.
 83. The method ofclaim 82 wherein the respiratory parameters comprise data representativeof one or more apneas and hypopneas experienced by the patient and datarepresentative of one or more Cheyne-Stokes epochs experienced by thepatient.
 84. The method of claim 67 wherein the non-contact sensor is anultrasonic sensing device.
 85. The method of claim 67 wherein thenon-contact sensor is a biomotion sensor.
 86. The method of claim 85wherein the non-contact sensor detects biomotion via low power pulses ofradio frequency energy.
 87. The method of claim 67 wherein thedetermining the heart failure condition change indicator is furtherbased on one of a group consisting of: a determined heart-ratevariability metric; a measure of sympathovagal balance; a measure of gasof the patient's blood; an oximetry measure; and a measure derived froma photoploethysmogram.
 88. A device for monitoring a patient to evaluatea heart failure condition of a patient comprising: a non-contact sensorconfigured to monitor the patient and to generate data representingpatient conditions; and a processor, coupled with the sensor, theprocessor configured to control a determination of a heart failurecondition change indicator based on the non-contact sensor data, theindicator representing information about a change in a heart failurecondition of the patient.
 89. The device of claim 88 wherein theprocessor is configured to: determine a respiratory parameter from thenon-contact sensor data; and compare the respiratory parameter with athreshold to determine the heart failure condition change indicator. 90.The device of claim 89 wherein the threshold is representative of achange to the respiratory parameter that is indicative of onset of acutedecompensation.
 91. The device of claim 89 wherein the respiratoryparameter is an apnea-hypopnea index.
 92. The device of claim 89 whereinthe respiratory parameter is a Cheyne-Stokes breathing pattern index.93. The device of claim 88 wherein the processor generates a warningbased on the heart failure condition change indicator.
 94. The device ofclaim 93 wherein the warning comprises a light signal.
 95. The device ofclaim 93 wherein the warning comprises an electronic message to betransmitted.
 96. The device of claim 88, further comprising atransmitter coupled with the processor, wherein the processor is furtherconfigured to control transmitting of a message including datarepresenting the heart failure condition change indicator.
 97. Thedevice of claim 88, further comprising: a patient interface; and a flowgenerator coupled to the processor and the patient interface, whereinthe processor is configured to control the generation by the flowgenerator of a flow of breathable gas at a pressure above atmospheric tothe patient interface.
 98. The device of claim 97, wherein thedetermination of the heart failure condition change indicator is furtherbased on a measure of pressure associated with the flow of breathablegas.
 99. The device of claim 98, wherein the measure of pressure is oneof: a peak inspiratory pressure; an end expiratory pressure; a medianpressure; a 95th percentile pressure; and a level of pressure support.100. The device of claim 88 wherein the processor is configured to:determine a plurality of respiratory parameters from the non-contactsensor data; and compare the respiratory parameters with respectivethresholds.
 101. The device of claim 100 wherein the respiratoryparameters comprise data representative of one or more apneas andhypopneas experienced by the patient and data representative of one ormore Cheyne-Stokes epochs experienced by the patient.
 102. The device ofclaim 88 wherein the non-contact sensor is an ultrasonic sensing device.103. The device of claim 88 wherein the non-contact sensor is abiomotion sensor.
 104. The device of claim 103 wherein the non-contactsensor detects biomotion via low power pulses of radio frequency energy.105. The device of claim 88 wherein the processor is further configuredto determine the heart failure condition change indicator based on oneof the group consisting of: a determined heart-rate variability metric;a measure of sympathovagal balance; a measure of gas of the patient'sblood; an oximetry measure; and a measure derived from aphotoploethysmogram.